#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>

#define LEN(a) (sizeof(a) / sizeof(a[0]))
#define MAX_MSG_LEN 100

typedef struct {
    unsigned int t;
    char* msg;
} Timers;

static Timers timers[] = {
    { 2400, "Time to start working!" },
    { 600,  "Time to start resting!" },
    { 2400, "Time to start working!" },
    { 600,  "Time to start resting!" },
    { 2400, "Time to start working!" },
    { 600,  "Time to start resting!" },
    { 2400, "Time to start working!" },
    { 1800,  "Time to take a longer rest!" },
};

void spawn(char* argv[])
{
    if (fork() == 0) {
        // we need to fork the process so that
        // when we exit the sent screen
        // this program continues.
        setsid();
        execvp(argv[0], argv);
        perror(" failed");
        exit(0);
    }
}

void print_time_now()
{
    time_t timer;
    char buffer[26];
    struct tm* tm_info;

    timer = time(NULL);
    tm_info = localtime(&timer);

    strftime(buffer, 26, "%Y-%m-%d %H:%M:%S", tm_info);
    fprintf(stderr, "%s", buffer);
}

void display_message(char* msg)
{
    char sh_command[MAX_MSG_LEN];
    snprintf(sh_command, MAX_MSG_LEN, "echo '%s' | sent", msg); // NOLINT: We are being carefull here by considering MAX_MSG_LEN explicitly.
    printf("%s", sh_command);
    char* spawn_args[] = {
        "/bin/sh",
        "-c",
        sh_command,
        NULL
    };
    spawn(spawn_args);
    print_time_now();
    fprintf(stderr, " | %s\n", msg);
}

int main(int argc, char* argv[])
{
    for (int i = 0;; i = (i + 1) % LEN(timers)) {
        display_message(timers[i].msg);
        sleep(timers[i].t);
    }
}